A small rock is thrown straight up with initial speed V0 from
the edge of the roof of a building with height H. The rock travels upward
and then downward to the ground at the base of the building. Let
+y be upward, and neglect air resistance. (a) For the rock’s motion from
the roof to the ground, what is the vertical component Vav-y of its average
velocity? Is this quantity positive or negative? Explain. (b) What
does your expression for Vav-y give in the limit that H is zero? Explain.
(c) Show that your result in part (a) agrees with Eq. (2.10).

Hugh D. Young, Roger A. Freedman - University Physics with Modern Physics (15th Edition) Chap. 3 Ex. 73

Answer:

C your answer would be C

Explanation:

It should be right

(a) The tension in the string is determined as 19.6 N.

(b) The acceleration of each object is 5.3 m/s².

(c) The distance each object will move in the first second if it started from rest is 2.65 m.

(a) The tension in the string is the resultant weight of the masses and magnitude is calculated as follows;

T = ( 5.7 kg - 3.7 kg ) x 9.8 m/s²

T = 19.6 N

(b) The acceleration of each object is calculated as follows;

a = T / m

where;

a = 19.6 N / 3.7 kg

a = 5.3 m/s²

(c) The distance each object will move in the first second if it started from rest is calculated as;

s = ut + ¹/₂at²

where;

s = 0 + ¹/₂(5.3)(1²)

s = 2.65 m

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(a) The mass of water is approximately 49.65 kg. (b) The final temperature of the water vapor will be 120°C. (c) The total enthalpy change is approximately 277,956 kJ. (d) Diagram shown below.

(a) To determine the mass of the water, we need to know its density at the given conditions. The density of water changes with temperature and pressure. At 40°C and 200 kPa, the density of water is approximately 993 kg/m³.

Since we have 50 L of water, we need to convert it to cubic meters:

50 L = 0.05 m³

Now we can calculate the mass of water:

Mass = Density * Volume

Mass = 993 kg/m³ * 0.05 m³

Mass ≈ 49.65 kg

Therefore, the mass of water is approximately 49.65 kg.

(b) To find the final temperature, we need to consider the phase change from liquid to vapor. At constant pressure, the temperature will remain constant until all the liquid water has vaporized. This temperature is called the saturation temperature.

We can determine the saturation temperature at 200 kPa using a steam table or other relevant data sources. Let's assume that the saturation temperature is 120°C.

Therefore, the final temperature of the water vapor will be 120°C.

(c) To calculate the total enthalpy change, we need to consider the energy required to heat the water from its initial temperature to the saturation temperature, as well as the energy required for the phase change from liquid to vapor.

The enthalpy change during heating can be calculated using the formula:

ΔH1 = Mass * Specific Heat Capacity * ΔT1

Where:

Mass = 49.65 kg (from part a)

Specific Heat Capacity = specific heat capacity of water at constant pressure = 4.18 kJ/(kg·°C)

ΔT1 = final temperature - initial temperature = 120°C - 40°C = 80°C

ΔH1 = 49.65 kg * 4.18 kJ/(kg·°C) * 80°C

ΔH1 ≈ 165,938 kJ

The enthalpy change during phase change can be calculated using the formula:

ΔH2 = Mass * Latent Heat of Vaporization

Where:

Mass = 49.65 kg (from part a)

Latent Heat of Vaporization = energy required to vaporize 1 kg of water = 2257 kJ/kg

ΔH2 = 49.65 kg * 2257 kJ/kg

ΔH2 ≈ 112,018 kJ

The total enthalpy change is the sum of ΔH1 and ΔH2:

Total Enthalpy Change = ΔH1 + ΔH2

Total Enthalpy Change ≈ 165,938 kJ + 112,018 kJ

Total Enthalpy Change ≈ 277,956 kJ

Therefore, the total enthalpy change is approximately 277,956 kJ.

(d) The process can be shown on a T-v (temperature-volume) diagram with respect to saturation lines. In this case, the process starts at the initial temperature and pressure (40°C, 200 kPa), and moves along the constant pressure line until reaching the saturation temperature (120°C). Then, the process follows the saturation line until the entire liquid is vaporized.

Here is a simplified representation of the process on a T-v diagram:

           |

Saturation |                       |

 Line   |                             |

           |                             |

           |                             |

           |                             |

           |                             |

           |                             |

           |                             |

 Initial |-----------------------------| Final

           |                             |

           |                             |

           |                             |

           |                             |

           |                             |

           |                            

This diagram is a rough representation and does not accurately reflect specific volume values or scale. It simply illustrates the general process from initial conditions to the final state along the constant pressure and saturation lines.

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Answer:

when air or water cools it sinks

(D)

Explanation:

The more massive an object is, the greater is the curvature that they produce on the space-time around it.

The theory of relativity explain the gravity exerted by massive objects is

more massive objects create larger curves of space-time (option-d).

The term "gravitational force" refers to the attraction between masses. The gravitational force increases in size as the masses get bigger (also called the gravity force). As the distance between masses grows, the gravitational force progressively lessens.

Greater gravitational forces will be used to attract heavier things since the gravitational force is directly proportional to the mass of both interacting objects. Therefore, when two things' respective masses increase, so does their gravitational pull to one another.

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Answer:

A: 1,212 kg

Explanation:

The spring is often when hydroelectric power is at its highest, when precipitation and snowmelt increase water runoff.

Seasonal patterns are observed in both hydroelectric and wind power generation. The spring, when precipitation and snowmelt boost water runoff, is usually when hydroelectric power is at its peak. Across the nation, there are different seasonal patterns for wind generation, but spring and fall often see the highest levels.

Windmills and wind turbines are two often used forms of wind power. Each of these is a type of kinetic energy, which is essentially everything that moves. Despite the fact that both are wind energy technologies, they have a number of significant variances, beginning with their anatomical structures.

Wind turbines of this kind are most frequently found. The majority of them feature two or three long, thin blades that resemble an airplane propeller. In order to face the wind directly, the blades are positioned in this manner.

Therefore, the correct answer is option B. All use generators to produce electrical current

The complete question is:

What do wind turbines, hydroelectric dams, and ethanol plants have in common?

A. All produce electrical current with pollution

B. All use generators to produce electrical current

C. All convert gravitational potential energy to electrical current

D. All convert thermal energy to electrical current

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The magnetic flux through the small loop when the current through the solenoid is 2.50 A is 5.87*10⁻⁴ Wb, the induced emf in the loop is 1.4*10⁻³r.

What is magnetic flux  ?

The number of magnetic field lines that travel through a specific closed surface is referred to as magnetic flux. It gives a measurement of the overall magnetic field that traverses a specific surface region.

What is  induced emf  ?

A magnetic field is induced when a conductor carrying an electric current travels through it. Induced electromagnetic fields (EMFs) are created when a magnetic field rotates around an electric field.

Given data

length = 0.100 m

radius = 0.50 m

N= 1.5 *10⁴

I= 2.50A

a) the field inside the solenoid  is

B= μ₀ Ni/L

B= 1.25 *10⁻⁶*1.5*10⁴*2.50/0.100

B= 0.47 Tesla

B= 0.47 W₆/m²

Area, A= πr²= (0.02)²

=0.00125m²

Magnetic flux = ∅ = B.A

= 5.87*10⁻⁴ Wb

b) induced Emf in the loop

EMf =  μ₀ (dI/dT) (N/L) πr²

EMF= 1.4*10⁻³r

Therefore, the magnetic flux through the small loop when the current through the solenoid is 2.50 A is 5.87*10⁻⁴ Wb, the induced emf in the loop is 1.4*10⁻³r.

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Answer:

hi what is your question?? say in English please

A 200 g hockey puck is launched up a metal ramp that is inclined at a 30° angle. The coefficients of static and kinetic friction between the hockey puck and the metal ramp are μs = 0.40 and μk = 0.30, respectively. The puck's initial speed is 3.8 m/s, Speed it will have when it slides back down to its starting point is 2.36 m/s

The resistance to motion of one object moving in relation to another is known as friction. It is not regarded as a fundamental force like gravity or electromagnetic, according to the International Journal of Parallel, Emergent and Distributed Systems(opens in new tab). The electromagnetic attraction between charged particles in two contacting surfaces, according to scientists, is what causes it.

using work energy theorem ,

change in kinetic energy = work done by frictional force

\(\frac{1}{2}\) m(\(x^{2}\)-\(y^{2}\)) =  μmghcos30°

where mass is m=200g

x is speed with which it slides back

y is speed at top of metal ramp=3.8 m/s

μ is coefficient of kinetic friction=0.3

g is gravity = 9.8m/\(s^{2}\)

h is height to which hockey puck is reached on metal ramp=1.18m

Substituting the values and solving for speed x,

x=2.36m/s

speed  it will have when it slides back down to its starting point is 2.36m/s

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Installing an underfloor heating system in a situation where the electricity is generated by a gas-fired plant would not be advantageous.

Charge or electrical supply flow is what is referred to as electricity. It is an alternative fuel source, which means we obtain it by transforming other natural resources into energy supplies, such as carbon, dirty energy, hydrocarbons, and nuclear energy.

To create electricity, a turbine set converts mechanical energy into electrical energy. The heat produced by sources of energy such natural gas, carbon, nuclear reactors, biomass, petroleum, volcanic, and solar heat is employed to transform to steam, which powers the rotors of turbines.

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Answer:

From the question we are told that

  The length of the rod is  \(L_o\)

    The  speed is  v  

     The angle made by the rod is  \(\theta\)

Generally the x-component of the rod's length is  

     \(L_x =  L_o cos (\theta )\)

Generally the length of the rod along the x-axis  as seen by the observer, is mathematically defined by the theory of  relativity as

       \(L_xo  =  L_x  \sqrt{1  - \frac{v^2}{c^2} }\)

=>     \(L_xo  =  [L_o cos (\theta )]  \sqrt{1  - \frac{v^2}{c^2} }\)

Generally the y-component of the rods length  is mathematically represented as

      \(L_y  =  L_o  sin (\theta)\)

Generally the length of the rod along the y-axis  as seen by the observer, is   also equivalent to the actual  length of the rod along the y-axis i.e \(L_y \)

    Generally the resultant length of the rod as seen by the observer is mathematically represented as

     \(L_r  =  \sqrt{ L_{xo} ^2 + L_y^2}\)

=>  \(L_r  = \sqrt{[ (L_o cos(\theta) [\sqrt{1 - \frac{v^2}{c^2} }\ \ ]^2+ L_o sin(\theta )^2)}\)

=>  \(L_r= \sqrt{ (L_o cos(\theta)^2 * [ \sqrt{1 - \frac{v^2}{c^2} } ]^2 + (L_o sin(\theta))^2}\)

=>   \(L_r  = \sqrt{(L_o cos(\theta) ^2 [1 - \frac{v^2}{c^2} ] +(L_o sin(\theta))^2}\)

=> \(L_r =  \sqrt{L_o^2 * cos^2(\theta)  [1 - \frac{v^2 }{c^2} ]+ L_o^2 * sin(\theta)^2}\)

=> \(L_r  =  \sqrt{ [cos^2\theta +sin^2\theta ]- \frac{v^2 }{c^2}cos^2 \theta }\)

=> \(L_o \sqrt{1 - \frac{v^2}{c^2 } cos^2(\theta ) }\)

Hence the length of the rod as measured by a stationary observer is

       \( L_r = L_o \sqrt{1 - \frac{v^2}{c^2 } cos^2(\theta ) }\)

   Generally the angle made is mathematically represented

\(tan(\theta) =  \frac{L_y}{L_x}\)

=>  \(tan {\theta } =  \frac{L_o sin(\theta )}{ (L_o cos(\theta ))\sqrt{ 1 -\frac{v^2}{c^2} } }\)

=> \(tan(\theta ) =  \frac{tan\theta}{\sqrt{1 - \frac{v^2}{c^2} } }\)

Explanation:

The special relativity relations allow to find the results for the questions about the measurements made by an observed at rest on the rod are:

     a) The length of the rod is: \(L = L_o \sqrt{1 - \frac{v^2}{c^2} \ cos^2\theta_o }\)  

     b) The angle with respect to the x axis is:   \(tan \theta = \frac{tan \theta_o}{\sqrt{1- \frac{v^2}{c^2} } }\)

Special relativity studies the motion of bodies with speeds close to the speed of light, with two fundamental assumptions.

If we assume that the two systems move in the x-axis, the relationship between the components of the length are:

        \(L_x = L_{ox} \ \sqrt{1- \frac{v^2}{c^2} }\)  

        \(L_y = L_o_y \\L_z = L_{oz}\)  

Where the subscript "o" is used for the fixed observed on the rod, that is, it is at rest with respect to the body, v and c are the speed of the system and light, respectively.

a) They indicate that the length of the rod is L₀ and it forms an angle θ with the horizontal.

Let's use trigonometry to find the components of the length of the rod in the system at rest, with respect to it.

         sin θ = \(\frac{L_{oy}}{L_o}\)  

         cos θ = \(\frac{L_{ox}}{L_o}\)  

         \(L_{oy}\) = L₀ sin θ

         L₀ₓ = L₀ cos θ

Let us use the transformation relations of the length of the special relativity rod.

x-axis

      \(L_x = (L_o cos \theta_o) \ \sqrt{1- \frac{v^2}{c^2} }\)  

y-axis  

      \(L_y = L_{o} sin \theta_o\)  

The length of the rod with respect to the observer using the Pythagorean theorem is:

      L² = \(L_x^2 + L_y^2\)  

      \(L^2 = (L_o cos \theta_o\sqrt{1- \frac{v^2}{c^2} })^2 + (L_o sin \theta_o)^2\)

      \(L_2 = L_o^2 ( cos^2 \theta_o - cos^2 \theta_o \frac{v^2}{c^2} + sin^2\theta_o)\)  

      \(L^2 = L_o^2 ( 1 - \frac{v^2}{c^2} \ cos^2 \theta_o)\)  

      \(L= Lo \sqrt{1- \frac{v^2}{c^2} cos^2 \theta_o}\)  

b) the angle with the x-axis measured by the stationary observer is:

     \(tna \theta = \frac{L_y}{L_x}\)

    \(tan \ theta = \frac{L_o sin \theta_o}{L_o cos \theta_o \sqrt{1- \frac{v^2}{c^2} } }\)  

    \(tan \theta = \frac{tan \theta_o}{\sqrt{1-\frac{v^2}{c^2} } }\)  

In conclusion, using the special relativity relations we can find the results for the questions about the measurements made by an observed at rest on the rod are:

      a) The length of the rod is:  \(L = L_o \sqrt{1- \frac{v^2}{c^2} \ cos^2\theta_o }\)

      b) The angle to the x axis is:  \(tan \theta = \frac{tan \theta_o}{\sqrt{1- \frac{v^2}{c^2} } }\)

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1) The force acting on the object during the time interval 0-3 seconds is 1/3 N.

2) The force acting on the object during the time interval 6-10 seconds is -0.5 N.

3) There is no time interval in which no force acts on the object.

(i) Force acting on the object in time interval 0-3 seconds. Force acting on the object is equal to the product of its mass and acceleration, i.e.,F = ma.

In the given velocity-time graph, the acceleration of the object can be determined by determining the slope of the velocity-time graph from 0 to 3 seconds.

Slope = (change in velocity) / (change in time)= (20-0) / (3-0) = 20/3 m/s^2

Acceleration, a = slope= 20/3 m/s^2

Mass of the object, m = 50 g = 0.05 kg

∴ Force acting on the object, F = ma= 0.05 × 20/3= 1/3 N.

Therefore, the force acting on the object during the time interval 0-3 seconds is 1/3 N.

(ii) Force acting on the object in time interval 6-10 seconds. Similar to the first question, the force acting on the object in time interval 6-10 seconds can be determined by determining the acceleration of the object during this time interval.

The slope of the velocity-time graph from 6 seconds to 10 seconds can be determined as follows:

Slope = (change in velocity) / (change in time)= (-20-20) / (10-6) = -40/4= -10 m/s^2 (negative sign indicates that the object is decelerating)

Mass of the object, m = 50 g = 0.05 kg

∴ Force acting on the object, F = ma= 0.05 × (-10)= -0.5 N.

Therefore, the force acting on the object during the time interval 6-10 seconds is -0.5 N.

(iii) Time interval in which no force acts on the object. There is no time interval in which no force acts on the object. This is because, as per Newton's first law of motion, an object will continue to remain in a state of rest or uniform motion along a straight line unless acted upon by an external unbalanced force.In other words, if the object is moving with a constant velocity, there must be a force acting on the object to maintain its motion.

Therefore, there is no time interval in which no force acts on the object.

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Answer:

Explanation:

The total amount of mass and energy in the universe is constant.....energy may change to mass and mass may change to energy, but the total is a constant.

Gerard's average velocity for the ride is 6 meters per second.

To find Gerard's average velocity for the ride, we can use the formula:

Average velocity = Total displacement / Total time

First, we need to convert the distance traveled from kilometers to meters:

7.20 kilometers * 1000 = 7200 meters

Next, we convert the time from minutes to seconds:

20.0 minutes * 60 = 1200 seconds

Now, we can calculate the total displacement by subtracting the initial position from the final position. Since Gerard is riding directly east, there is no change in the east-west direction, so the displacement is equal to the distance traveled:

Total displacement = 7200 meters

Finally, we substitute the values into the average velocity formula:

Average velocity = 7200 meters / 1200 seconds

Average velocity = 6 meters per second

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Answer:

Maximum range is achieved by launching the projectile at an  angles of 45 degrees.

so the answer is B

Explanation:

What is the range of a projectile?

this can be defined as the maximum horizontal distance covered by a projectile

R=v^2sin(2θ)/2g

Why is 45 degrees maximum range?

"The sine function reaches its largest output value, 1, with an input angle of 90 degrees, so we can see that for the longest-range puts 2θ = 90 degrees and, therefore, θ = 45 degrees."

Hence a projectile, travels the farthest when it is launched at an angle of 45 degrees

Answer:

a) 0.47MW

b) 39.24%

Explanation:

In order to find the power needed for the elevator to operate at its maximum capacity, we can make use of the following formula:

P=Fv

where P is the power, F is the force and v is the velocity.

The force the elevator must carry can be calculated with the following formula:

F=mg

where m is the mass of the elevator and g is the acceleration of gravity, so:

\(F=(8000 kg)(9.81 m/s^{2})\)

F=78 480 N

so now we can make use of the power formula:

P=Fv

P=(78 480N)(6 m/s)

P=470 880W

P=0.47W

b)

In order to find the efficiency, we will suppose that the generator can generate a maximum of 0.47 W so we use the following formula:

\(efficiency = \frac{P_{in}}{P_{out}}*100\%\)

\(efficiency=\frac{0.470880}{1.2}*100\%\)

efficiency=39.24%

Answer:

which on a is the question

Answer: a) 123.1m

b) 279.1m

Explanation:

The maximum height reached by the rocket is 0 meters. The rocket's greatest horizontal range beyond point A is also 0 meters.

To find the maximum height, we can use the kinematic equation for vertical motion. The rocket starts from rest, so its initial vertical velocity is 0 m/s. We can use the equation:

\(h = vi^2 / (2 * g)\)

where h is the maximum height, vi is the initial vertical velocity, and g is the acceleration due to gravity. We can calculate h by substituting the given values:

h = (0 m/s)2 / (2 * 9.8 m/s2)

= 0 m

Therefore, the maximum height reached by the rocket is 0 meters above the ground.

To find the rocket's greatest horizontal range, we can use the horizontal motion equations. Since the rocket is subject to gravity only after leaving the incline, we need to find the time it takes for the rocket to reach the highest point on the incline. We can use the equation:

t = vf / a

where t is the time, vf is the final velocity, and a is the acceleration. We can calculate t by substituting the given values:

t = 3.50/ 3.50

= 1s

Now we can use the equation for horizontal motion to find the horizontal range:

\(R = v0 * t\)

where R is the horizontal range and v0 is the initial horizontal velocity. Since the rocket starts from rest, v0 = 0 m/s. Therefore, the rocket's greatest horizontal range beyond point A is 0 meters.

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Explanation:

third and fifth option along with the first one are right

Answer: B

Explanation: The best answer is B. A baseball thrown by a professional pitcher. Momentum is the product of an object's mass and its velocity. Since the baseball has the greatest velocity of all the objects listed, it has the greatest momentum.

Answer:

An object is in motion when its distance from another object is changing. A reference point is a place or object used for comparison to determine if something is in motion. An object is in motion if it changes position relative to a reference point.

option C is your CORRECT answer

The torque that is produced at the center of the drum is 50 Nm.

The term torque has to do with a force that leads to a turning effect. I can use the example of a tap to show you what is meant by a torque. The force that is exerted on a tap causes the tap to turn and this is what we mean by saying that a torque would produce a turning effect.

We have the following;

Force = 250 N

Distance = 20 cm or 0.2 m

Torque = 250 N  *  0.2 m

= 50 Nm

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Answer:

it will  decrease

Explanation:

According to the law of universal gravitation, the gravitational force exerted by the moon on the spacecraft is equal to the product of their masses and inversely proportional to the square of the distance that separates them. Therefore, as the spacecraft moves away, its distance increases and the force of attraction exerted by the moon decreases.

Answer:

A. It will increase

Explanation:

I took the quiz on K12 and this was the correct option.

Hope I helped

Answer:

Explanation:

10.00 5

The steps assume that the mirrors and boxes are arranged in a simple, two-dimensional configuration.

The steps to be followed are;

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Answer:

- They need oxygen to burn fuel

- Aerodynamics

- Extreme temperatures

- Radiation

- Pressure issues

Explanation:

A airplane is a heavier-than-air aircraft kept aloft by the upward thrust exerted by the passing air on its fixed wings and driven by propellers, jet propulsion, etc.

Aeroplanes cannot travel in space for several reasons:

They need oxygen to burn fuel - Aeroplane engines rely on the oxygen in the atmosphere to burn fuel and generate thrust. In space, there is no atmosphere so there is no oxygen for the engines to work.

Aerodynamics - Aeroplane wings generate lift by interacting with the air. In space, there is no air so wings would be unable to generate any lift. Aeroplanes rely on aerodynamics to fly which does not work in space.

Extreme temperatures - In space, temperatures can range from -150 degrees Celsius to 150 degrees Celsius. Aeroplanes are designed to operate within a much narrower temperature range. The extreme cold and heat of space could damage aeroplane components.

Radiation - In space, there are high levels of radiation from the Sun and cosmic rays. Aeroplane bodies are not designed to shield against this type of radiation and it could damage electronics and affect aeroplane systems.

Pressure issues - Aeroplanes are designed to withstand air pressures at altitudes up to around 12 kilometers. In low-Earth orbit and beyond, the air pressure is essentially zero. This extreme change in pressure could cause structural damage to the aeroplane.

In summary, while aeroplanes are designed to fly through the Earth's atmosphere, they lack the key features needed to operate in the extreme environment of outer space like spaceships. Aeroplanes require things like oxygen, aerodynamics and being able to withstand changes in pressure - all of which do not exist or work the same way in space.

Explanation:

The wing is pushed up by the air under it. Large planes can only fly as high as about 7.5 miles. The air is too thin above that height. It would not hold the plane up.

Answer:

Individual H2O molecules are V-shaped, consisting of two hydrogen atoms (depicted in white) attached to the sides of a single oxygen atom (depicted in red). Neighboring H2O molecules interact transiently by way of hydrogen bonds (depicted as blue and white ovals).

Answer:

tough

ques

Explanation: